STABLE STATES IN SURFACE-EMITTING SEMICONDUCTOR-LASERS

We consider a vertical cavity surface-emitting semiconductor laser whi ch operates with two frequency-degenerate doughnut modes, and combinat ions thereof. We identify a small region in the parameter space, where there is bistability between the two doughnut states, and another dom ain in which the TEM(10) mode, and all the configurations obtained fro m it by rotation around the laser axis, are stable. The degeneracy by rotation can be eliminated by considering a pump region of square sect ion; in this case there is bistability between two stationary states, in which the two intensity peaks are located along the diagonals of th e square. In all the rest of the parameter space the system exhibits d ynamical oscillations.